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Design and FPGA implementation of a log-domain high-speed fuzzy control system Open Access


Other title
fuzzy controller, defuzzification, log-domain, FPGA
Type of item
Degree grantor
University of Alberta
Author or creator
Razib, Md Ali
Supervisor and department
Dick, Scott (Electrical and Computer Engineering)
Gaudet, Vincent (Electrical and Computer Engineering)
Examining committee member and department
Reformat, Marek (Electrical and Computer Engineering)
Amaral, Nelson (Computing Science)
Department of Electrical and Computer Engineering

Date accepted
Graduation date
Master of Science
Degree level
The speed of fuzzy controllers implemented on dedicated hardware is adequate for control of any physical process, but too slow for today’s high-complexity data networks. Defuzzification has been the bottleneck for fast implementations due to the large number of computationally expensive multiplication and division operations. In this thesis, we propose a high-speed fuzzy inferential system based on log-domain arithmetic, which only requires addition and subtraction operations. The system is implemented on a Xilinx Virtex-II FPGA with a processing speed of 67.6 MFLIPS having a maximum combinational path delay of 4.2 ns. It is a clear speedup compared to the reported fastest 50 MFLIPS implementation. A pipelined version of the controller is also implemented, which achieves a speed of 248.7 MFLIPS. Although a small approximation error is introduced, software simulation and hardware implementation on FPGA confirm high similarity of the outputs for control surfaces and a number of second-order plants.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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